New problem: SIM error!

So recently my 1520.3's touchscreen has really started to go crazy beyond the normal tap/scroll issue, with buttons activating themselves launching cortana, the back button and random elements on the screen. Now I seem to have another problem, sometimes the phone will just somehow lose the SIM card and i'll get a "SIM error" message when I turn it on requiring a reboot for the phone to connect to the network again.

Has anyone had this happen to them, and could the two possibly be related? I've got quotes for a screen replacement but if this is another unrelated problem I might just go back to my 1020 instead of spending money on what could be a major repair. Thanks.

The "SIM Error" is usually caused by two things: a really old SIM card or corrosion or dirt on the surface of the SIM Card (also common in old SIM cards). You may want to check the integrity of the contacts of the SIM card first. If they are not as "golden" as how the new SIM cards are, you may try restoring the luster back by gently rubbing a pencil eraser on the contact points.

Sometimes, just removing and reinserting the SIM card will make it work - but that usually because the process of removing and reinserting the card clears out some of the corrosion on the surface of the contact points.

You may also try using your SIM card in a different phone and see if the error persists for that card. If it does, then you most probably need to have the card replaced - this has happened to me before, but only after having the same SIM card for more than eight years.